The present invention relates to a convertible-type motor vehicle. More particularly this invention concerns a folding roof or top for such a vehicle.
A standard motor-vehicle convertible top normally comprises a folding framework overlain by a flexible cover. The frame is comprised of a plurality of rigid struts or hoops. The cover normally comprises a waterproof outer layer, an intermediate sound- and heat-insulating layer, and an inner head liner layer. The framework typically is hidden between the inner and outer layers. It allows the top to move between a folded-down position normally recessed behind the passenger compartment and an up position stretched over the passenger compartment and connected to the upper edge of the windshield.
The top described in German patent 196 16 891 of H. Schanzer has generally tubular connecting clips that are stitched to a liner bonded to the outer layer. Thus the stitching securing these clips in place is not exposed externally so as to present a leak site. While this arrangement does very securely mount the cover on the framework, it is fairly complex.
German utility model 297 18 206 describes another top where mounting strips secure the support struts directly to the outer layer and the intermediate layer is pinched between the outer layer and the struts. The top structure is fairly complex, requiring many steps to secure the various parts together. In the finished top there is a thermal bridge between the outer layer and the struts formed by the mounting strips.
U.S. Pat. No. 6,082,807 of Hartmann describes an arrangement where a strip-shaped polyurethane casting is used to secure a windshield in a hole in the cover. This polyurethane strip can be extended around splice or stiffener elements also.
Further arrangements described in German utility models 69 445 15, 92 06 366, and 92 09 122 and in German patents 4,221,570 of W. Braun and 4,441,670- of M. Aydt are similarly complex. Their assembly is a complex operation and they often leave sites for water or heat to get through the top. The support struts are secured to the outer layer from which the intermediate insulating layer is suspended, or the latter is itself mounted on the struts.
It is therefore an object of the present invention to provide an improved motor-vehicle convertible top.
Another object is the provision of such an improved motor-vehicle convertible top which overcomes the above-given disadvantages, that is which is of simple construction but where the cover is solidly connected to the framework without the possibility of leakage.
A motor-vehicle convertible top has according to the invention a foldable and waterproof cover having an inner face, a framework having a plurality of rigid struts juxtaposed with the inner face, a foam-plastic layer unitarily bonded to the inner face, and connecting elements integral with the foam-plastic layer and secured to the struts so that the framework is connected via the elements to the cover. The connecting elements can be imbedded in the foam-plastic layer or unitarily formed with the foam-plastic layer.
Thus with this system there is no stitching, adhesive, or welding needed to secure the connecting element to the cover. Instead it is anchored in the molded-on foam-plastic layer which can also serve as the heat- and sound-insulating intermediate layer of the cover. Thus the foam-plastic layer, which serves to secure the cover to the framework, serves double duty, and even stiffens the cover so that it will not deform and bulge outward during high-speed travel. In fact the foam-plastic layer can generally cover the entire inner surface of the cover and function as the sound- and heat-insulating intermediate layer.
The connecting elements in accordance with the invention are strips complementarily fittable with the struts. They may grip around the struts like clips or be simple formations that fit with and are screwed to the struts of the framework.
According to the invention the foam-plastic layer is polyurethane having a Shore D hardness of about 40 and is a two-component resin having a polyol:isocyanate ratio of about 100:38 by weight. It has a thickness of 2 mm to 8 mm.
The cover according to the invention has stitched seams and the foam-plastic layer covers and seals the seams. This completely solves the problem of how to waterproof the cover at these critical seams between the panels that make up the outer waterproof layer of the cover.
The cover in accordance with the invention includes reinforcing bands extending along ends of the struts. The foam-plastic layer extends over the bands. The foam-plastic layer also extends over a full length of each of the bands.
The cover includes a waterproof outer layer forming the inner surface and the foam-plastic layer can be formed as strips extending on the inner surface along the struts. These strips impart a soft curve to the cover where it passes over the strut for best appearance and aerodynamic properties. What is more, the foam-plastic layer that covers generally all of the inner surface can be interrupted at fold lines to facilitate folding of the cover in the closed position of the top.